Multi-layer substrates comprising sandwich layers and polyethylene

ABSTRACT

Multi-layer substrates comprising a top surface layer of pulp fibers, a bottom surface layer of pulp fibers, and a melted thermoplastic material layer between the pulp fiber layers, where the thermoplastic material comprises polyethylene or has a tan delta value of 0.2 to 0.4 within the temperature range of 100° F. to 350° F. The multi-layer substrate can include a cleaning composition loaded onto the multi-layer substrate, where a fluid pathway through the melted thermoplastic material allows the cleaning composition to travel from the top surface layer to the bottom surface layer. The multi-layer substrate may be void of chemical adhesives, where adhesion between the top surface layer and the thermoplastic layer, and between the bottom surface layer and the thermoplastic layer is instead provided by the thermoplastic material itself, which bonds to groups of fibers in the pulp fibers top and bottom surface layers that are in contact with the thermoplastic material as it melts.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication No. 62/860,655, filed on Jun. 12, 2019, U.S. ProvisionalPatent Application No. 62/828,301, filed Apr. 2, 2019 and U.S.Provisional Patent Application No. 62/784,274 filed on Dec. 21, 2018.The disclosure of each of the foregoing is herein incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION 1. The Field of the Invention

The present invention relates to cleaning wipes, more particularly topre-moistened cleaning wipes that are formed from multi-layersubstrates.

2. Description of Related Art

Numerous cleaning wipes are available, e.g., such as CLOROX DISINFECTINGWIPES. While such wipes provide good overall cleaning and disinfectioncharacteristics, versatility, and convenience, there is a continuingneed for improved cleaning wipes, as well as methods for theirmanufacture.

BRIEF SUMMARY

The present invention relates to wipes that may typically bepre-moistened during manufacture, where the wipe includes a multi-layersubstrate comprising two or more layers, in which the wipe as a whole(on a dry basis) comprises greater than 70% by weight pulp fibers (e.g.,75% to 90% pulp fibers). By forming the vast majority of the substratefrom pulp, the resulting wipe is more sustainably sourced, whilepotentially providing a simpler manufacturing process, and potentiallyoffering improvements in the dosing characteristics and/or efficacyprovided by the wipe. Various other fibrous nonwovens, such asmeltblown, spunbond, spunlaid, SMS (spunbond-meltblown-spunbond),coform, airlaid, wetlaid, carded webs, thermal bonded, through-airbonded, thermoformed, spunlace, hydroentangled, needled, chemicallybonded, or combinations thereof may also be used.

An embodiment may be directed to a multi-layer substrate (e.g., a wipe)including a top surface layer that consists essentially of pulp fibersformed by at least one of the following processes: airlaid, wetlaid,carded webs, thermal bonded, through-air bonded, thermoformed,hydroentangled, needled, chemically bonded, or pulp fibers, such astissue paper (e.g., no significant load of synthetic fibers therein), amelted thermoplastic material comprising polyethylene (e.g., where themelted thermoplastic material layer is configured a thin film layer), abottom surface layer that consists of any of the materials listedrelative to the top layer (e.g., similar or identical to the top layer),and a cleaning composition loaded onto the multi-layer substrate.Because the thermoplastic layer at the interior of the “sandwich”structure has been melted, there is a fluid pathway provided through themelted thermoplastic material layer, which allows the cleaningcomposition to travel from the top surface layer to the bottom surfacelayer, through the fluid pathway of the thermoplastic material layer.The multi-layer substrate may be void of any chemical adhesives,including but not limited to: water based adhesives, hot melt adhesives,tackifying agents or resins, waxes, plasticizers, and the like, forholding the plurality of layers together. Binders may technically bepresent in a tissue paper or other pulp layers (e.g., in relativelysmall amounts) because such binders are frequently used in processingpulp material layers, although the purpose of such included binders,like kymene (PAE), is to impart strength to the pulp fibers duringprocessing to create the pulp layer, rather than for any purpose ofactually adhering a layer of pulp material to a thermoplastic materiallayer. Instead, the melted thermoplastic material bonds to groups offibers (e.g., pulp fibers) in the top and bottom layers which were incontact with the thermoplastic material as it melted.

Another embodiment is directed to a multi-layer substrate comprising atop surface layer consisting essentially of at least one of: airlaid,wetlaid, carded webs, thermal bonded, through-air bonded, thermoformed,spunlace, hydroentangled, needled, chemically bonded, or pulp fibers,e.g., tissue paper, a bottom surface layer consisting essentially of atleast one of airlaid, wetlaid, carded webs, thermal bonded, through-airbonded, thermoformed, spunlace, hydroentangled, needled, chemicallybonded, or pulp fibers, e.g., tissue paper, and a melted thermoplasticmaterial layer between the top and bottom pulp layers, where thethermoplastic material has a tan delta value of 0.2 to 0.4 within thetemperature range of 100° F. to 350° F. The multi-layer substrate canalso include a cleaning composition loaded onto the multi-layersubstrate, where a fluid pathway through the melted thermoplasticmaterial allows the cleaning composition to travel from the top surfacelayer to the bottom surface layer. The multi-layer substrate may be voidof chemical adhesives, where adhesion between the top surface layer andthe thermoplastic layer, and between the bottom surface layer and thethermoplastic layer is instead provided by the thermoplastic materialitself, which bonds to groups of fibers in the top and bottom layersthat are in contact with the thermoplastic material as it melts.

The referenced tan delta value is defined as the ratio of viscousmodulus divided by elastic modulus. It therefore provides informationrelative to the ratio of a material's viscous liquid phase stiffness orflow characteristics relative to the material's solid phase stiffnesscharacteristics. Different polymeric materials exhibit different tandelta characteristics, and this ratio also varies for a given materialwith temperature. Polyethylene is an exemplary material that exhibits atan delta value in a range of 0.2 to 0.4 within the temperature range of100° F. to 350° F. Other polymeric materials (e.g., polypropylene) donot necessarily exhibit such characteristics. Applicant has found thattan delta is a good indicator of whether a given polymeric material willresult in a melted thermoplastic “sandwich” layer that effectively bondsto the nonwoven layers both above and below the thermoplastic inner“sandwich” layer, while at the same time opening up fluid pathwaysthrough the thermoplastic layer, allowing liquids (e.g., a cleaningcomposition) to flow between the top and bottom layers, through thethermoplastic layer.

Another embodiment relates to a method of manufacturing a multi-layersubstrate, including providing both top and bottom surface layers, e.g.,each consisting essentially of any of the nonwovens identified above,providing a thermoplastic film material layer (e.g., initiallyimpervious to liquid) that comprises polyethylene and/or has a tan deltavalue of 0.2 to 0.4 within the temperature range of 100° F. to 350° F.,and heating the film material layer to a temperature at which thethermoplastic film material softens, opening pores through the film orbreaks in the film, so as to provide a fluid pathway through thethermoplastic film layer so that any liquid loaded onto the top surfacelayer is able to pass through the fluid pathway, to the bottom surfacelayer. Once so formed, the multi-layer substrate can be loaded with acleaning composition, e.g., by applying the cleaning composition to thetop and/or bottom surface layer(s). Because of the fluid pathway, fluidcommunication is possible from one surface layer to the other, throughthe fluid pathway in the thermoplastic film layer.

During such manufacturing, pressure can be applied with the applicationof heat during formation of the fluid pathway through the thermoplasticmaterial. The application of heat, and optional application of pressureat the same time, may serve to bond the thermoplastic material to groupsof fibers in the top and bottom layers that are in contact with thethermoplastic material as it softens, such that no chemical adhesivesare used to adhere the top and bottom layers to the thermoplasticmaterial.

Further features and advantages of the present invention will becomeapparent to those of ordinary skill in the art in view of the detaileddescription of preferred embodiments below.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of thepresent invention, a more particular description of the invention willbe rendered by reference to specific embodiments thereof which areillustrated in the drawings located in the specification. It isappreciated that these drawings depict only typical embodiments of theinvention and are therefore not to be considered limiting of its scope.The invention will be described and explained with additionalspecificity and detail through the use of the accompanying drawings.

FIGS. 1A-1D show schematic views of exemplary multi-layer substratetextures with various dot patterns.

FIG. 1E is a photograph showing 4 different exemplary multi-layersubstrate textures that were actually formed, each with differentlysized unbonded raised texture features (i.e., raised dots).

FIG. 2 is an SEM image of the top surface of an exemplary multi-layersubstrate, showing two adjacent unbonded raised regions, with the bondedregion extending there-between.

FIG. 3 shows an SEM image of an cross-sectional or edge view through anexemplary multi-layer substrate such as that of FIG. 2, showing the pulpfiber top surface layer, the pulp fiber bottom surface layer, and thethermoplastic film layer sandwiched there-between, where there are bothbonded regions, and regions in which the thermoplastic layer and theadjacent pulp fiber surface layer are unbonded relative to one another.

FIG. 4 is a chart showing elastic modulus and tan delta values versustemperature for polyethylene, polypropylene, and for a polymer comprisedof “bicomponent” fibers, i.e., a (“bico”) polymer.

FIGS. 5A-5B illustrate various exemplary wipes packages, showing how thepresent multi-layer substrate wipes can be pulled through a typical wipepack orifice, without significant shredding of the exterior pulp fiberslayers.

FIG. 6 is an SEM image showing spunbond thermoplastic fibers envelopingadjacent pulp fibers of the adjacent top surface layer.

FIGS. 7A-7F illustrate additional exemplary textures and patterns.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS I. Definitions

Before describing the present invention in detail, it is to beunderstood that this invention is not limited to particularlyexemplified systems or process parameters that may, of course, vary. Itis also to be understood that the terminology used herein is for thepurpose of describing particular embodiments of the invention only, andis not intended to limit the scope of the invention in any manner.

All publications, patents and patent applications cited herein, whethersupra or infra, are hereby incorporated by reference in their entiretyto the same extent as if each individual publication, patent or patentapplication was specifically and individually indicated to beincorporated by reference.

The term “comprising” which is synonymous with “including,”“containing,” or “characterized by,” is inclusive or open-ended and doesnot exclude additional, unrecited elements or method steps.

The term “consisting essentially of” limits the scope of a claim to thespecified materials or steps “and those that do not materially affectthe basic and novel characteristic(s)” of the claimed invention.

The term “consisting of” as used herein, excludes any element, step, oringredient not specified in the claim.

It must be noted that, as used in this specification and the appendedclaims, the singular forms “a,” “an” and “the” include plural referentsunless the content clearly dictates otherwise. Thus, for example,reference to a “surfactant” includes one, two or more surfactants.

Unless otherwise stated, all percentages, ratios, parts, and amountsused and described herein are by weight.

Numbers, percentages, ratios, or other values stated herein may includethat value, and also other values that are about or approximately thestated value, as would be appreciated by one of ordinary skill in theart. As such, all values herein are understood to be modified by theterm “about”. Such values thus include an amount or state close to thestated amount or state that still performs a desired function orachieves a desired result. A stated value should therefore beinterpreted broadly enough to encompass values that are at least closeenough to the stated value to perform a desired function or achieve adesired result, and/or values that round to the stated value. The statedvalues include at least the variation to be expected in a typicalmanufacturing or other process, and may include values that are within10%, within 5%, within 1%, etc. of a stated value.

Some ranges may be disclosed herein. Additional ranges may be definedbetween any values disclosed herein as being exemplary of a particularparameter. All such ranges are contemplated and within the scope of thepresent disclosure.

In the application, effective amounts are generally those amounts listedas the ranges or levels of ingredients in the descriptions, which followhereto. Unless otherwise stated, amounts listed in percentage (“%'s”)are in weight percent (based on 100% active) of any composition.

The phrase ‘free of’ or similar phrases if used herein means that thecomposition or article comprises 0% of the stated component, that is,the component has not been intentionally added. However, it will beappreciated that such components may incidentally form thereafter, undersome circumstances, or such component may be incidentally present, e.g.,as an incidental contaminant.

The phrase ‘substantially free of’ or similar phrases as used hereinmeans that the composition or article preferably comprises 0% of thestated component, although it will be appreciated that very smallconcentrations may possibly be present, e.g., through incidentalformation, contamination, or even by intentional addition. Suchcomponents may be present, if at all, in amounts of less than 1%, lessthan 0.5%, less than 0.25%, less than 0.1%, less than 0.05%, less than0.01%, less than 0.005%, less than 0.001%, or less than 0.0001%. In someembodiments, the compositions or articles described herein may be freeor substantially free from any specific components not mentioned withinthis specification.

As used herein, “disposable” is used in its ordinary sense to mean anarticle that is disposed or discarded after a limited number of usageevents, preferably less than 25, more preferably less than about 10, andmost preferably after a single usage event. The wipes disclosed hereinare typically disposable.

As used herein, the term “substrate” is intended to include any materialthat is used to clean an article or a surface. Examples of cleaningsubstrates include, but are not limited to, wipes, mitts, pads, or asingle sheet of material which is used to clean a surface by hand or asheet of material which can be attached to a cleaning implement, such asa floor mop, handle, or a hand held cleaning tool, such as a toiletcleaning device. The term “substrate” is also intended to include anymaterial that is used for personal cleansing applications. Thesesubstrates can be used for hard surface, soft surface, and personal careapplications. Such substrates may typically be in the form of a wipe.

Such substrates may be formed of a structure of individual fibers whichare interlaid, typically in a manner that is not identifiable, similarto a nonwoven. The top and bottom surface layers or pulp layers includedin the present substrates may be formed by any suitable process,typically through wetlaying, although airlaying may also be possible.Various processes for forming various other nonwovens will be apparentto those of skill in the art, many of which are described in U.S. Pat.No. 7,696,109, incorporated herein by reference in its entirety. Pulpfibers may generally be ribbon-shaped, rather than the generallycircular fiber geometry of synthetic fibers commonly used in syntheticnonwovens, and which may be present in the thermoplastic layer of thepresent substrates. The thermoplastic layer may be provided as asynthetic nonwoven, formed according to any desired process. Thethermoplastic layer may also be a film, rather than being comprised offibers. The basis weight of any of the multiple layers of the substratemay be expressed in grams per square meter (gsm). Basis weight of suchsubstrates is often also expressed in “pounds” (e.g., referring tolbs/3000 ft² of the tissue paper).

The terms “wipe”, “substrate” and the like may thus overlap in meaning,and while “wipe” may typically be used herein for convenience, it willbe appreciated that this term may often be interchangeable with“substrate”.

As used herein, “wiping” refers to any shearing action that the wipeundergoes while in contact with a target surface. This includes hand orbody motion, substrate-implement motion over a surface, or anyperturbation of the substrate via energy sources such as ultrasound,mechanical vibration, electromagnetism, and so forth.

The cleaning compositions dosed onto the substrate as described hereinmay provide sanitization, disinfection, or sterilization, othercleaning, or other treatment. As used herein, the term “sanitize” shallmean the reduction of “target” contaminants in the inanimate environmentto levels considered safe according to public health ordinance, or thatreduces a “target” bacterial population by significant numbers wherepublic health requirements have not been established. By way of example,an at least 99% reduction in bacterial population within a 24 hour timeperiod is deemed “significant.” Greater levels of reduction (e.g.,99.9%, 99.99%, etc.) are possible, as are faster treatment times (e.g.,within 10 minutes, within 5 minutes, within 4 minutes, within 3 minutes,within 2 minutes, or within 1 minute), when sanitizing or disinfecting.

As used herein, the term “disinfect” shall mean the elimination of manyor all “target” pathogenic microorganisms on surfaces with the exceptionof bacterial endospores.

As used herein, the term “sterilize” shall mean the complete eliminationor destruction of all forms of “target” microbial life and which isauthorized under the applicable regulatory laws to make legal claims asa “sterilant” or to have sterilizing properties or qualities. Someembodiments may provide for at least a 2 or more log reduction (e.g.,3-log reduction, or 6-log reduction) in a bacterial population within adesignated time period (e.g., 10 minutes, 5 minutes, 4 minutes, 3minutes, 1 minute, 30 seconds, 10 seconds or the like). A 2-logreduction is equivalent to a 99% reduction, a 3-log reduction isequivalent to at least a 99.9% reduction, a 4-log reduction isequivalent to at least a 99.99% reduction, a 5-log reduction isequivalent to at least a 99.999% reduction, etc. An example of a targetmicrobe may be Staphylococcus aureus. It will be appreciated thatmicroefficacy can also be achieved against other target microbes,numerous examples of which will be apparent to those of skill in theart. It will also be appreciated that the present cleaning compositionsneed not include an antimicrobial agent, where sanitization ordisinfection is not necessarily desired.

The term “texture” as used herein refers to the character or appearanceof a substrate as determined by the arrangement and thickness of itsconstituent fibers. In at least some instances, texture can bequantified using imaging techniques and/or caliper measurements at thelocal and macro scales, as described in Applicant's application Ser. No.16/042,690, filed Jul. 23, 2018, herein incorporated by reference in itsentirety. By way of explanation, “patterns” are typically visual, withareas of discernable contrast. “Texture” is typically tactile, andrelates to variations relative to the normal plane of the substrate(i.e., 3-dimensional texture in the substrate). Visual pattern andtactile texture interact in a complex manner with a user'svisual/tactile sense of sight and touch to produce a given aestheticperception for a given substrate, in addition to other quantifiabletechnical characteristics associated with such.

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which the invention pertains. Although a number of methodsand materials similar or equivalent to those described herein can beused in the practice of the present invention, the preferred materialsand methods are described herein.

II. Introduction

In an aspect, the present invention is directed to multi-layersubstrates including at least 3 layers, in which the exterior faces ofthe wipe are provided (e.g., exclusively) by structured plant basedfibers, such as structured wood pulp fibers (e.g., tissue paper,conventional paper, paper towels etc.), or at least one of meltblown,spunbond, spunlaid, SMS (spunbond-meltblown-spunbond), coform, airlaid,wetlaid, carded webs, thermal bonded, through-air bonded, thermoformed,spunlace, hydroentangled, needled, or chemically bonded, fibers. Wetlaidmaterials include both nonwoven materials as well as materials made inpapermaking processes, such as tissue paper, conventional paper, etc.Where used, the term “tissue” is used for convenience, and it will beappreciated that it is intended to be broadly construed, includingtissue paper materials, as well as other similar materials formed frompulp. An interior “sandwich” layer comprising a thermoplastic materialis provided, between the tissue or other pulp layers (or other top andbottom layers), which adheres the entire multi-layer substrate togetherin a single mass, with low risk of delamination, while providing desiredcharacteristics relative to hand-feel, stiffness, absorbency (ability toload the substrate to a desired loading ratio with a cleaningcomposition), while also providing a fluid pathway through thethermoplastic layer through which the cleaning composition can migratefrom the top pulp fiber layer, to the bottom pulp fiber layer, or viceversa. Because the thermoplastic layer melts in contact with pulp fibersof the adjacent tissue or other pulp layers, and particularly given thetan delta characteristics of the thermoplastic material, the meltsoftened thermoplastic material encapsulates, envelops, wraps, orotherwise coats individual adjacent pulp fibers of the tissue layer,providing a strong bond between the two adjacent layers, such thatdelamination does not readily occur. In addition, the thermoplasticlayer typically does not penetrate through the tissue or other pulplayers, so that no synthetic fibers or synthetic layer material is onthe exposed exterior faces of the wipe. This results in the advantagethat relatively softer pulp fibers are used for wiping and cleaningversus contact with harder more abrasive synthetic fibers. The wipe isthus less harsh on the surfaces being treated and does not cause anymechanical scratching, abrasion, or erosion.

Such multi-layer substrates may be formed through a thermal and pressurecalendaring process in which top and bottom surface pulp fiber layersare provided (e.g., the tissue or other layers are provided preformed),and a thermoplastic film layer comprising polyethylene or anotherpolymer having suitable tan delta values is also provided. Manycommercially available multi-layer hard surface cleaning substrates haveexternal layers made of thermoplastic materials such as polyethylene,polypropylene, PET, and other suitable synthetic materials. Typically, alayer of pulp fibers is positioned in the middle of the syntheticmaterial layers so that the pulp fibers are not lost through abrasionduring the cleaning process. In contrast, an embodiment of the presentinvention has the opposite configuration where the layers of pulpmaterials are in a top surface layer and a bottom surface layer and thethermoplastic material is between the pulp material layers.

The layers may be assembled (e.g., with the tissue layers as “bread”sandwiching the thermoplastic film layer (as “cheese”) therebetween),followed by subjecting the assembly to heat (and typically pressure) ata temperature that melt softens the thermoplastic material. This heatingopens pores through the thermoplastic film, e.g., even if the film wasinitially impervious to liquid, while also softening the thermoplasticmaterial so that it wraps around or otherwise coats the adjacent pulpfibers of the top and bottom tissue layers, effectively tying theadjacent layers to one another, without any chemical adhesive to preventthe layers from delaminating or pulling apart from one another. At thesame time that this layer bonding occurs, any impervious filmcharacteristics that previously existed with respect to thethermoplastic layer are broken, so that a fluid pathway is createdthrough the thermoplastic layer, through which a cleaning composition orother liquids applied to either the top or bottom tissue layer canpenetrate from one tissue layer to the other tissue layer, through thethermoplastic film layer.

Once the dry substrate has been formed, a desired cleaning compositionmay be loaded onto the multi-layer substrate. Because of the presence ofthe fluid pathway, even if the cleaning composition is loaded as aliquid only one of the top or bottom layers, it will flow through thesubstrate to the other exterior layer through the broken thermoplasticfilm layer.

III. Exemplary Multi-Layer Substrates

FIGS. 1A-1D illustrate exemplary wipes 100 a-100 d, each with adifferent applied surface texture and bonding pattern, but where each isconfigured as a multi-layer substrate including a melted thermoplasticfilm layer sandwiched between top and bottom pulp fiber layers. Whileshown with various textures, it will be appreciated that numerous othertextures could be provided, or perhaps no texture at all. Additionalexemplary textures are shown in FIGS. 7A-7F. FIG. 1E shows photographsof 4 exemplary multi-layer wipes 100 a-100 d that were actuallymanufactured for evaluation.

FIG. 2 shows a close up of one of the raised ridges 102 of one of theexemplary wipes, showing how the raised circular ridge 102 (a “dot”) isunbonded to the thermoplastic film layer disposed therebelow, such thatthere is actually a gap there-between, at the ridge 102. The region 104surrounding the raised ridge 102 is bonded (and is so labeled) to theunderlying thermoplastic film layer disposed therebelow. Depending onthe particular applied textured pattern, the bonded region 104 may becontiguous, as shown (i.e., there is a single contiguous bonded region,rather than multiple bonded regions that are fully separated from oneanother). In other words, by “contiguous”, one can reach any particularlocation in the bonded region from any other particular location in thebonded region, by traversing only other bonded regions, without any needto traverse an unbonded region. The bonded region 104 may thus becontiguous, even though it does not cover the entire top exterior face(or bottom exterior face) of the wipe, because there are spaced apartunbonded regions 102. Stated another way, by analogy, the unbondedregions may be configured as “islands” in a “sea” of the bonded region.It will be appreciated that other configurations are of course possible.

The texture may be an embossed texture that is applied during a thermalcalendaring or other manufacturing operation that laminates the 3 layersof the “sandwich” structure together. Alternatively, the texture couldhave been introduced into the substrate structure as a result of thegeometry used in the forming screen used during the tissue makingprocess, when depositing the pulp fibers that make up the tissuelayer(s).

From FIG. 2, it is apparent that the pulp fibers of the top surfacelayer (as well as the bottom surface layer) are ribbon shaped, ratherthan being generally circular in cross-section, as is the case withtypical synthetic fibers of non-woven substrates. Such ribbon-shapedfibers rather have a generally rectangular cross-section, as opposed tobeing circular in cross-section. FIG. 3 is an SEM image of an end orcross-section through an exemplary multi-layer substrate, such as thatof FIG. 2, showing the thermoplastic film layer 106 (labeled “Bico”)sandwiched between a through-air-dried (“TAD”) pulp fiber top surfacelayer 108 a, and a TAD pulp fiber bottom surface layer 108 b. Alsolabeled in FIG. 3 is a bonded region 104, as well as an unbonded region,adjacent a raised ridge “dot” of the bottom pulp fiber layer 108 b. Inthis labeled unbonded region, there is a gap between the thermoplasticlayer 106 and the bottom pulp fiber layer 108 b. While in this regionthe bottom pulp fiber layer 108 b is unbonded, in this same region, thethermoplastic layer 106 may (or may not be) bonded to the top pulp fiberlayer 108 a. In other words, the unbonded characteristic may apply toone or both faces of the thermoplastic layer.

a. Pulp Characteristics

The fibrous portion of the top and bottom surface layers of themulti-layer substrates may be formed predominantly, and in an embodimententirely, from pulp fibers, e.g., wood pulp or other plant fibers. Evenwhere the thermoplastic layer is clearly not comprised of such pulpfibers (as it is instead a synthetic thermoplastic polymeric material,(e.g., having particular tan delta value characteristics), the substrateas a whole is one in which a majority of the fiber weight of thesubstrate is pulp. For example, greater than 70% (by weight) of thefibers of the substrate may be pulp fibers. In an embodiment 75% to 90%,75% to 85%, or 75% to 80% of the fibers in the substrate may be pulpfibers, by weight. In other words, synthetic fibers may account for lessthan 30%, such as 10% to 25%, 15% to 25%, or 20% to 25% by weight of thefibers. Such is the case where the thermoplastic film layer is a fibrousfilm (e.g., a thin spunbond film). It will be appreciated that inanother embodiment, the thermoplastic film may not necessarily befibrous, e.g., such as in the case of a cast or “bubble” blown film thatis not made up of numerous fibers, but is simply a continuous thin(e.g., cast) sheet. In such an embodiment, the thermoplastic materialmay still account for less than 30%, 10% to 25%, 15% to 25%, or 20% to25% of the dry substrate, but may simply be in non-fibrous form (e.g., acast sheet). In such a case, technically, 100% of the fibers of thesubstrate may be pulp fibers.

In an embodiment, all fibers of the top surface layer and bottom surfacelayer may consist of or consist essentially of pulp fibers. For example,these layers may not include any synthetic fibers, or any syntheticstructural components (e.g., no synthetic fillers). By forming themulti-layer substrates from a high fraction of pulp, the substrates maybe more sustainably sourced, e.g., where a higher fraction of thecomponents used are derived from sustainable sources as compared to,e.g., existing wipes formed from a blend of pulp and synthetic fibers.

The pulp fibers may typically be obtained from wood, although otherpossible sources of pulp are also possible, e.g., from cotton, Espartograss, bagasse, hemp, flax, jute or the like. Combinations of more thanone material may be used. Various exemplary pulp fibers may include, butare not limited to, thermomechanical pulp fibers, chemimechanical pulpfibers, chemithermomechanical pulp fibers, refiner mechanical pulpfibers, stone ground wood pulp fibers, peroxide mechanical pulp fibers,and the like. The fibers of the pulp substrate may generally comprisecellulosic fibers, which are typically hydrophilic. Such hydrophilicitydiffers from many synthetic fibers, which are typically hydrophobic,absent special treatment.

Additional details relative to exemplary pulp fibers are found inApplicant's application Ser. No. 16/042,690, filed Jul. 23, 2018,already herein incorporated by reference herein. Such characteristicscan be specifically selected to ensure sufficient quat release, as wellas other characteristics.

The top and bottom pulp fiber layers of the multi-layer substrate mayhave a basis weight of no more than 50 lbs, no more than 40 lbs, no morethan 30 lbs, or no more than 20 lbs, at least 3 lbs, at least 5 lbs, orat least 10 lbs, such as from 7 lbs to 20 lbs, or 8 lbs to 15 lbs. Such“lbs” values refer to the weight per/3000 ft², as will be appreciated bythose of skill in the art.

In an embodiment, the top and bottom pulp fiber layers do not includeany added synthetic fibers, e.g., such as various polyolefins or otherfibers formed from synthetic polymers, e.g., polyethylene,polypropylene, PET, PVC, polyacrylics, polyvinyl acetates, polyvinylalcohols, polyamides, polystyrenes, or the like. While such syntheticfibers are widely used in the manufacture of nonwoven substrates,Applicant seeks to reduce the use of such non-sustainable materials, andhas found that by limiting or eliminating their use in the top andbottom exterior surface layers, additional benefits can be provided. Forexample, the present wipes can provide functional parity, and sometimesadvantages, over conventional nonwoven wipes in durability, safety foruse on all surfaces, ease and convenience, ability to clean and absorblight liquid spills, ability to clean large areas effectively, andmicroefficacy in the case of sanitization or disinfection. Furthermore,the use of significant quantities of synthetic resins in existingpre-moistened nonwoven wipes represents a significant expense, such thatcost savings, renewability and sustainability benefits, andbiodegradability benefits can be achieved using pulp substrates, asdescribed herein.

The individual layers of the top and bottom pulp fiber layers that areused in manufacturing the multi-layer substrate can be formed by any ofa number of different techniques, e.g., such as any of those suitablefor use in forming tissue layers. Examples include, but are not limitedto wet-laying and air-laying, as well as conventional press-drying, andthrough-air drying techniques. Wet-laying methods are used in makingboth nonwoven materials and paper products, including but not limitedto: conventional paper, tissues, towels, napkins, and they like. Methodsof making such substrate layers will be apparent to those of skill inthe art. Wet-laying processes are described in U.S. Pat. Nos. 5,246,772and 5,238,534 to Manning. Air-laying processes are described in U.S.Patent Publication No. 2003/0036741 to Abba et al. and U.S. PatentPublication No. 2003/0118825 to Melius et al. Conventional processes bywhich a manufactured substrate in a wet condition is pressed to removeprocess water, as well as through-air-drying processes will be familiarto those of skill in the art. In an embodiment, the top and bottomtissue layers are formed by through-air-drying.

Various techniques for forming nonwoven top or bottom layers that areairlaid, wetlaid, carded webs, thermal bonded, through-air bonded,thermoformed, spunlace, hydroentangled, needled, or chemically bondedwill be apparent to those of skill in the art, some of which aredescribed in U.S. Pat. No. 7,696,109, already incorporated by reference.

Where tissue layers are used, one or both of the tissue layers maycomprise more than a single ply, or each may comprise only a single ply.Where multiple plies are provided, they may be adhered together, so asto have adequate peel strength, e.g., as described in Applicant'sapplication Ser. No. 16/042,690, filed Jul. 23, 2018, alreadyincorporated by reference. Where only a single ply is present in each ofthe top and bottom tissue layers, no chemical adhesive may be presentanywhere in the multi-layer substrates. Where two plies are used ineither or both of the tissue layers, a chemical adhesive may be presentin the tissue layers (i.e., between plies), but may not be presentbetween the thermoplastic layer and the adjacent top and bottom tissuelayers.

b. Thermoplastic Layer

The present multi-layer wipes include a sandwich structure in which athermoplastic layer is provided, on the inside of the wipe, sandwichedbetween the pulp fiber layers. Where no chemical adhesive is used toadhere the 3 layers into an integral, single structure that does notreadily delaminate between layers, but in which the thermoplasticmaterial itself is used for this purpose, the Applicant has found thatnot just any thermoplastic polymer will be suitable for such a purpose.For example, in testing various thermoplastic polymers, Applicant foundthat various materials, even upon heating, will not readily bond to theadjacent pulp fiber layer, but will form a very weak bond, if any atall. Such weak bonding is of course unacceptable in a multi-layersubstrate to be used as a cleaning wipe, where delamination must beavoided. In the present invention, the multi-layer substrates havesufficient adhesion between the layers that they do not delaminate evenwhen wet (e.g., allowed to soak for weeks, in storage) or when used forcleaning hard surfaces. The thermoplastic layer not only binds themulti-layer substrate together as it melts, but it also imparts strengthto the exterior layers of pulp fibers or tissue paper. It is surprisingthat this binding of the pulp layer occurs so well that there is not anysignificant shredding of the exterior pulp layer, e.g., as themulti-layer substrate is pulled through a typical wipe dispensingorifice.

For example, Applicant found that while polypropylene may seem like asuitable thermoplastic material to achieve such bonding between the topand bottom pulp fiber layers separated by the thermoplastic materiallayer, polypropylene did not provide good bonding, but resulted in weakbonding and delamination between the 3 layers. Applicant found a keycharacteristic or indicator as to whether a given thermoplastic materialwould work, is tan delta value. Tan delta value is an engineeringcharacteristic that can be evaluated for thermoplastic polymericmaterials, and gives information relative to how much “liquid” viscousphase characteristics dominate versus “solid” elastic phasecharacteristics, in a given material, at a given temperature. Tan deltais simply calculated as the ratio of viscous modulus divided by elasticmodulus for a given material, at a given temperature. To measure the tandelta value, strips were cut from the nonwoven materials withapproximate dimensions 13 mm L×10 mm W×0.07 mm T, with the longestdimension along the machine direction. The strips were clamped into theDMA tensile fixture, and oscillated at 1 Hz while ramping up thetemperature up 5 degrees C./minute.

FIG. 4 charts both tan delta and elastic modulus values for 3 testedthermoplastic materials—polyethylene, polypropylene, and a bicomponentmaterial that comprises polyethylene. For example, the bicomponentmaterial tested is believed to be comprised of bicomponent fibers, witha fiber core (that is not polyethylene), and an exterior coating on thecore, that is polyethylene. FIG. 4 charts both elastic modulus and thetan delta value for these 3 materials over the temperature range ofabout 100° F. to 350° F. FIG. 4 shows how the elastic modulus (i.e.,stiffness) of the polypropylene is the highest, followed by the “bico”,followed by the polyethylene, and that the stiffness of each decreaseswith increasing temperature.

The tan delta value for the polypropylene is very low, less than 0.2,and remains less than 0.15 at temperatures from 100° F. to over 300° F.It isn't until nearly 350° F. that the tan delta value increasessomewhat, but only slightly, up to a value of about 0.15, and certainlystill less than 0.2. The polyethylene tan delta value is quitedifferent, being about 0.2 at a temperature of 100° F., and increasingto about 0.25 to 0.3 at about 175° F.-190° F. After peaking at aroundthis temperature, the tan delta value begins to decrease, to 0.2 atabout 250° F., and dropping somewhat below 0.2 (e.g., about 0.18) atabout 260°-270° F. Tan delta for the “bico” is between that of thepolypropylene and the polyethylene for much of the temperature range,until about 250° F. where it is higher than the polyethylene. Both thepolyethylene and the “bico” material (which comprises polyethylene)include points along the temperature range of 100° F. to 350° F. wheretan delta is at least 0.2 (e.g., greater than 0.2 to 0.4, or greaterthan 0.2 to 0.3). The polypropylene tan delta never reaches 0.2 overthis temperature range of 100° F. to 350° F. Thus, in an embodiment, theselected thermoplastic material for the “sandwich” layer has a tan deltavalue that is at least 0.2 (e.g., from 0.2 to 0.4, or from 0.2 to 0.3)somewhere within the temperature range of 100° F. to 350° F. In anembodiment, the selected thermoplastic material may have such a tandelta value at the particular temperature at which the thermalcalendaring step is performed (e.g., 150° F., 175° F., 200° F., 225° F.,250° F., 275° F., 300° F., 325° F., etc.) or at any narrower rangewithin the temperature range of 100° F. to 350° F.

The selected thermoplastic material may advantageously have a meltingtemperature that is less than 400° F., less than 375° F., less than 350°F., less than 325° F., less than 300° F., at least 150° F., at least175° F., at least 200° F., or at least 225° F. Having a relatively lowermelting temperature of course reduces energy requirements needed in thecalendaring process, but may also be particularly important given theuse of tissue paper exterior layers, where paper ignites at 451° F. Evenbelow such an ignition temperature, there may be undesirable changes inthe tissue paper (e.g., discoloration, embrittlement, etc.). As such,selection of lower melting temperature thermoplastic materials may bepreferred, so long as they can provide a good bond to the tissue layers.

FIGS. 5A-5B show how the present multi-layer substrates may be packagedwithin any of various exemplary flex packs (FIG. 5A), cylinders (FIG.5B) or other containers for storage and dispensing. The wipes 100 may bepulled through an orifice such as typically provided with suchcontainers, without fear of shredding or delamination of the variouslayers. In particular, Applicant tested prototype wipes such as shown inFIG. 1E by pulling them through orifices (e.g., as seen in FIGS. 5A-5B),and there was no significant shredding of the exterior tissue layers, ordelamination of the layers from one another. Rather, each wipe was ableto be pulled through the orifice, remaining fully intact, time aftertime. FIG. 6 shows an SEM image at the interface between a spunbondfibrous thermoplastic layer 106 and an adjacent exterior tissue layer(e.g., 108 a) showing how the pulp fibers at the interface are wrappedaround, enveloped, or coated by the melt-softened thermoplasticmaterial, that occurs during the thermal calendaring process. Thisstrong connection between the pulp fiber layer and the thermoplasticlayer provides a strong bond, so that shredding or delamination do notoccur when pulling the wipe through a typical wipe pack orifice. Thesecharacteristics are believed to result because of the tan deltacharacteristics of the thermoplastic material described above inconjunction with FIG. 4.

FIG. 5B further shows how such wipes may be packaged as a “donut”, e.g.,in a cylindrical container. The ability to package the wipes in such adonut configuration is somewhat surprising, given the high pulp content(e.g., 75-80% pulp) of the substrate. For example, it is difficult topackage pre-dosed 100% pulp substrates in such a configuration withoutthe donut collapsing or creasing vertically, due to insufficientstiffness of the substrate.

The thermoplastic film layer is not required to be particularly thick.For example, the thermoplastic film layer may have a thickness of 0.01mm to 0.1 mm, or 0.01 mm to 0.05 mm. It may be so thin as to betransparent or translucent, prior to assembly into the sandwichstructure.

c. Cleaning Composition

Many cleaning composition components as known within the art may besuitable for use in the present pre-dosed wipes. In an embodiment, thecleaning composition is an aqueous composition, including at least 90%water by weight (e.g., 90% to 99% water). The composition may include0.05% to 5% by weight of a quaternary ammonium compound, and/or 0.1% to5% by weight of a glycol ether solvent. For example, the quaternaryammonium compound may be included from 0.05%, from 0.1%, up to 5%, up to4%, up to 3%, up to 2%, or up to 1% by weight of the cleaningcomposition. The glycol ether solvent may be included from 0.1%, from0.25%, up to 5%, up to 4%, up to 3%, up to 2%, or up to 1% by weight ofthe cleaning composition. Other solvents, surfactants, and various otheradjuvants often included in cleaning compositions may optionally bepresent. While some embodiments may include lower alcohol solvents(e.g., C₁-C₄ alcohols), the amount of such volatile solvents may belimited, e.g., to less than 10%, less than 5%, less than 3%, less than2%, or less than 1% by weight. In some embodiments, the composition maybe free of, or substantially free of, such lower alcohol or other highlyvolatile solvents.

Quaternary ammonium compounds have broad spectrum antimicrobialproperties. A variety of different quaternary ammonium compounds can beused in the cleaning composition. Non-limiting examples of quaternaryammonium compounds are typically halides (e.g., a chloride) ofalkyldimethylbenzylammonium, alkyldimethylethylbenzylammonium,alkyldimethylammonium, or the like. The alkyl groups of such quaternaryammonium compounds may typically range from C₁₂ to C₁₈. Quaternaryammonium compounds are described in more detail in U.S. Pat. No.6,825,158, incorporated by reference herein, and will already befamiliar to those of skill in the art.

Organic acids can also be used to provide antimicrobial properties. Byway of example, such an organic acid may be included in an amount of atleast 0.1%, or at least 0.5%, up to 5%, up to 4%, up to 3%, up to 2%, orup to 1% by weight of the cleaning composition.

The cleaning composition may include a glycol ether solvent. Exemplaryglycol ether solvents include, but are not limited to, ethylene glycolmonopropyl ether, ethylene glycol monobutyl ether, propylene glycoln-propyl ether, propylene glycol monobutyl ether, propylene glycolt-butyl ether, diethylene glycol monoethyl or monopropyl or monobutylether, di- or tri-polypropylene glycol methyl or ethyl or propyl orbutyl ether, acetate and/or propionate esters of glycol ethers.

Those of skill in the art will appreciate that any among a wide varietyof surfactants (e.g., anionic, cationic, non-ionic, zwitterionic, and/oramphoteric) may be included in the cleaning composition, as desired.Where included, a surfactant may be present from 0.05%, from 0.1%, up to10%, up to 5%, up to 4%, up to 3%, up to 2%, or up to 1% by weight ofthe cleaning composition. Various surfactants and other optionaladjuvants are disclosed in U.S. Pat. No. 3,929,678 to Laughlin andHeuring, U.S. Pat. No. 4,259,217 to Murphy, U.S. Pat. No. 5,776,872 toGiret et al.; U.S. Pat. No. 5,883,059 to Furman et al.; U.S. Pat. No.5,883,062 to Addison et al.; U.S. Pat. No. 5,906,973 to Ouzounis et al.;U.S. Pat. No. 4,565,647 to Llenado, and U.S. Publication No.2013/0028990. The above patents and applications are each hereinincorporated by reference in their entirety.

As used herein the term “liquid” and “cleaning composition” includes,but is not limited to, solutions, emulsions, suspensions and so forth.Thus, liquids may comprise and/or contain one or more of the following:disinfectants; antiseptics; diluents; surfactants, such as nonionic,anionic, cationic; waxes; antimicrobial agents; sterilants; sporicides;germicides; bactericides; fungicides; virucides; protozoacides;algicides; bacteriostats; fungistats; virustats; sanitizers;antibiotics; pesticides; and so forth. Examples of some such componentsare included in, but not limited to, U.S. Pat. Nos. 6,825,158;8,648,027; 9,006,165; 9,234,165, and U.S. Publication No. 2008/003906each of which is herein incorporated by reference in its entirety. Insome embodiments, it may be possible to provide the substrates in dryform, where dosing with a selected cleaning composition may occur later(e.g., by the user).

With regard to pre-moistened substrates, a selected amount of liquid maybe added to the container or wipes during manufacture such that thecleaning substrates contain the desired amount of liquid. The substratesare not necessarily loaded to their saturation point, but are typicallyloaded with the cleaning composition to some ratio less than fullsaturation. For example, many substrates are capable of holding about 8to 14 times their weight in liquid. For reasons described herein, thesubstrates may be loaded at a loading ratio less than saturation, e.g.,less than 6:1, less than 5:1, less than 4:1, such as from 1:1 to 4:1,from 2:1 to 4:1, from 2.5:1 to 3.5:1, from 2.5:1 to 3:1 or from 2.5:1 to3.75:1.

d. Other Characteristics

The size and shape of the wipe can vary with respect to the intendedapplication and/or end use of the same. The cleaning substrate can havea substantially rectangular shape of a size that allows it to readilyengage standard cleaning equipment or tools such as, for example, mopheads, duster heads, brush heads, mitten shaped tools for wiping orcleaning, and so forth. In another embodiment, another shape, e.g.,circular, oval, or the like) may be provided.

The wipes or other cleaning substrates may be provided pre-moistenedwith a cleaning composition. The wet cleaning substrates can bemaintained over time in a sealable container such as, for example,within a bucket or tub with an attachable lid, sealable plastic pouchesor bags, canisters, jars, and so forth. Desirably the wet, stackedcleaning substrates are maintained in a resealable container. The use ofa resealable container is particularly desirable when using aqueousvolatile liquid compositions since substantial amounts of liquid canevaporate while using the first sheets thereby leaving the remainingsheets with little or no liquid. Exemplary resealable containers anddispensers include, but are not limited to, those described in U.S. Pat.No. 4,171,047 to Doyle et al., U.S. Pat. No. 4,353,480 to McFadyen, U.S.Pat. No. 4,778,048 to Kaspar et al., U.S. Pat. No. 4,741,944 to Jacksonet al., U.S. Pat. No. 5,595,786 to McBride et al.; the entire contentsof each of the aforesaid references are incorporated herein byreference.

Typically, the cleaning substrates are stacked and placed in thecontainer and the liquid subsequently added thereto, all during massmanufacturing. It is advantageous that the thermoplastic layer at thecenter of each wipe not be liquid impervious, to facilitate easierloading of the wipes. As described herein, even if the thermoplasticfilm as initially provided before lamination of the 3 layers together isliquid impervious, Applicant has found that cracks or other fluidpathways are opened up within the film during thermal calendaring, ascontemplated herein. While this may not necessarily occur with any andall thermal calendaring operations, it does occur under the conditionscontemplated herein.

The presence of such cracks or other fluid pathways that are opened upduring manufacture of the multi-layer substrate advantageously allowliquid cleaning composition dosed on either face of the substrate tomigrate through the wipe, to the opposite exterior face, through thethermoplastic film layer. This similarly allows dosed cleaningcomposition to migrate from one substrate to the next, e.g., where thesubstrates are stacked (e.g., by wicking the liquid from one to thenext). For example, a given volume or weight of the cleaning compositionmay simply be dosed into the bottom of the container, allowing it towick into the stack of wipes. In the case of a donut configuration, byplacing the cleaning composition into the bottom of the cylindricalcontainer, an end of each wipe actually make simultaneous contact withthe cleaning composition in the bottom of the container, where it can bewicked up into the height of each wipe (and the height of the donut).This may actually occur with a donut configuration whether thethermoplastic film layer were “broken” to include the described fluidpathways or not (i.e., if it remained impervious), as both the top andbottom pulp fiber layers will contact the cleaning composition at thebottom of the container simultaneously. Where any initially liquidimpervious characteristics of the film are “broken” by the thermalcalendaring process, this may further aid the cleaning composition inwicking upwards throughout the full height of each wipe, and the donutas a whole.

No matter the packaging and dosing process, once manufactured andpackaged, the substrate can subsequently be used to wipe a surface. Themoistened cleaning substrates can be used to treat various surfaces. Asused herein “treating” surfaces is used in the broad sense and includes,but is not limited to, wiping, polishing, swabbing, cleaning, washing,disinfecting, scrubbing, scouring, sanitizing, and/or applying activeagents thereto.

The wipes or other cleaning substrates of the present invention can beprovided in a kit form, wherein a plurality of cleaning substrates and acleaning tool are provided in a single package.

In addition to material composition and construction (e.g., tissuesubstrates on the exterior, thermoplastic layer only on the inside, noton the exposed face, composition of the cleaning “lotion” and the like),wipe or other substrate dimensions can also be used to control dosing aswell as provide ergonomic appeal. In one embodiment, substratedimensions are from about 5½ inches to about 11 inches in length, andfrom about 5½ inches to about 11 inches in width to comfortably fit in ahand. The substrate can have dimensions such that the length and widthdiffer by no more than about 2 inches. Larger substrates may be providedthat can be used and then folded, either once or twice, so as to containdirt within the inside of the fold and then the wipe can be re-used.Such larger substrates may have a length from about 5½ inches to about13 inches and a width from about 10 inches to about 13 inches. Suchsubstrates can be folded once or twice and still fit comfortably in thehand.

While most synthetic or blended nonwoven substrates used in wipemanufacture exhibit significant differences in tensile strength in themachine direction (MD) versus the cross direction (CD), the presentmulti-layer substrates may exhibit values in each direction that resultin a ratio of MD/CD that is relatively close to 1, e.g., such as 0.5 to1.5, 0.75 to 1.25, or 0.8 to 1.2. In other words, the substrates may besubstantially isotropic with respect to their tensile strength. Suchsubstantially isotropic characteristics reduce the likelihood of therebeing problems when folding substrates into stacks for packaging, orforming donuts for packaging.

Various other characteristics relating to stiffness, strength, densityof pulp fibers, wet bulk factor, profile height, pore volumedistribution characteristics, retention characteristics, lotionretention, MABDF, and others that may be provided by the present wipesare described in Applicant's application Ser. No. 16/042,690, filed Jul.23, 2018, already incorporated herein by reference.

e. Antimicrobial Efficacy & Other Characteristics

Exemplary multi-layer substrates were tested for their ability toeffectively deliver an antimicrobial quaternary ammonium compound to asurface during simulated cleaning. Applicant notes that the generallyanionic characteristics of typical pulp substrates lead to a tendency ofthe substrate to bind or otherwise retain the cationic quaternaryammonium compound, even when squeezing an aqueous cleaning compositionincluding such a quat from the substrate. In other words, typically, theconcentration of quaternary ammonium compound in the “squeezate” (thecleaning composition as squeezed from the pre-loaded wipe) is less thanthe concentration of quaternary ammonium compound in the cleaningcomposition before it was loaded into the wipe. Since quaternaryammonium compounds are known to bind to pulp substrates, it wasunexpected that the present wipes were able to release a significantenough portion of the quaternary ammonium compound to achievedisinfectancy and/or sanitization on a treated surface without theinclusion of any biocide release agent or latex binder in the substrate.Even more surprising was that even though the tested substrate wascomprised of 78% pulp fibers by weight, when compared to a blendedsubstrate including 60% pulp fiber by weight, the present substratesexhibited greater quat release in the “squeezate” as compared to thecomparative wipe, which included lower pulp content.

Because of these interesting and advantageous characteristics, there maynot be a need to increase the quat concentration in the cleaningcomposition, in order to achieve a desired level of microefficacy, ascompared to that used in the comparative wipe. For example, commerciallyavailable disinfecting wipes often contain about 0.1 to 5%, andpreferably 0.1 to 3%, and more preferably 0.1 to 2% by weight of quat inthe cleaning composition. Surprisingly, despite the fact that themulti-layer substrates of the present invention have higher levels ofpulp they also have good microefficacy performance with 0.1 to 3%, andpreferably 0.1 to 2% by weight of quat in the cleaning composition. Inan embodiment, the wipes release at least 40%, at least 50%, at least55%, at least 60%, or at least 65% of the quaternary ammonium compound(i.e., quaternary ammonium compound in the squeezate as compared to thecleaning composition before loading). The wipes may exhibit at least a3-log reduction in a target microbe, such as Staphylococcus aureus,within a given time frame (e.g., such as 5 minutes, 4 minutes, 3minutes, 1 minute, 30 seconds, 10 seconds, etc.).

Table 1 shows the results of testing in which a cleaning compositionincluding a quaternary ammonium compound was loaded into a substrateaccording to the present invention, and as compared to a conventionalblended substrate. The cleaning composition was squeezed from bothsubstrates, and the squeezate was analyzed to determine the reduction inthe concentration of the quaternary ammonium compound in the squeezatecompared to the composition as loaded.

TABLE 1 Substrate % Quat Released 60/40 blended substrate - 51%comparative example 78/22 exemplary multi-layer 69% substrate

The ability to achieve higher quat release while including higher pulpcontent is particularly surprising and unexpected. This characteristicadvantageously allows for better relative microefficacy characteristics.This high quat release may be due to the presence of absorptive pocketsor gaps, e.g., such as seen in FIG. 3, adjacent the unbonded regions.Such gaps provide a significant absorptive region between thethermoplastic film layer and the unbonded raised region 102, which canserve as a reservoir for the cleaning composition. Such regions allowsignificant quantities of the cleaning composition to be stored withinthe substrate, to be released upon squeezing, wiping, or othercompression, where there is reduced contact between the quat in thecomposition and any anionic binding sites associated with the pulpfibers of the exterior surface layer. This combination of the reservoirsbeing partially bounded by the inert thermoplastic film material (whichdoes not include significant concentration of anionic binding sites), incombination with the gaps associated with the reservoirs themselves isbelieved to at least partially account for the ability to release suchhigh fractions of the quat upon squeezing the wipe.

Other characteristics of the comparative and exemplary substrates areshown in Table 2 below.

TABLE 2 60/40 blended substrate - 78/22 exemplary Characteristiccomparative example multi-layer substrate Basis weight 52 gsm 55 gsm (26lb tissue layers + 12 gsm thermoplastic layer Composition 60/40 78/22 (%pulp/% synthetic) Caliper (wet - mm) 0.6 0.76 Absorbency (g) 12 12Tensile Strength 4.61/1.63 3.48/3.06 (MD/CD - lb_(f)) Dry Stiffness 285500 (mg · cm) Carrier release total - 0.49/0.63 0.58/0.56 S₁/S₂ (g)Visible Pattern Snake Medium dot (100 c)

By way of further explanation the dot patterns and textures shown inFIG. 1E included smallest dots (100 b), small dots (100 c), medium dots(100 a), and large dots (100 d). The wet thickness of the resultingsubstrates is affected by the dot pattern or texture. For example, aflat sample (not shown) had a wet thickness of 0.3 mm, the sample 100 a(smallest dots) had a wet thickness of 0.39 mm, the sample 100 b (smalldots) had a wet thickness of 0.65 mm, the sample 100 c (medium dots) hada wet thickness of 0.66 mm, and sample 100 d (large dots) had a wetthickness of 0.83 mm. The forgoing values are for substrates with onlyone tissue layer textured. Two sided samples include somewhat higher wetthickness values.

The dosed exemplary multi-layer substrate was tested for microefficacyagainst Staphylococcus aureus at a loading ratio of 3.75:1, using anexisting quat cleaning composition, at a contact time of 3 min 30 sec.The control population of 6.1 log was reduced to 0 in each of 60replicates. Testing was performed under 5% soil load conditions. Suchresults indicated excellent efficacy against Staphylococcus aureus at a3:30 contact time.

The dosed wipes were also tested for efficacy in various other householdcleaning tasks, including cleaning kitchen grease (KG) and bathroom scum(BS). The results of such testing demonstrated parity or near paritywith the comparative wipe, as shown below in Table 3.

TABLE 3 % soil % soil Cycles to Cycles to removal at 30 removal at 3075% removal - 75% removal - Substrate cycles - KG cycles - BS KG BS60/40 blended substrate - 96.87 96.62 4 7 comparative example 78/22exemplary 97.92 96.2 6 9 multi-layer substrate

The small increase in cycles for 75% removal may be due to the absenceof synthetic fibers on the exterior surface and reduced tendency of thepresent wipes to “dump” cleaning composition, as compared to thecomparative example blended wipe. The reported values represent averagesfor two sides of the wipes. The conventional wipe “dumps” or releasesmore liquid from the first side, thereby requiring few cycles to clean,but also reducing mileage. This “dumping” characteristic is described inApplicant's application Ser. No. 16/042,690, filed Jul. 23, 2018,already incorporated by reference.

As mentioned, the present wipes do not include any synthetic fibersexposed at the exterior faces of the wipe, but any synthetic fibers arerather located only within the interior of the wipe (and potentiallyincidentally exposed at the edges). As a result, the exterior surfacemay be soft, rather than abrasive. While Applicant did prepare someprototype substrates that did include synthetic fibers on the exteriorsurfaces (i.e., using a blend of pulp and synthetic fibers to form theexterior “tissue layers”, the resulting wipes did not provide the samedesired hand-feel characteristics as were provided where the exteriorpulp fiber or tissue layers did not include exposed synthetic fibers.While 100% pulp fibers on the exterior faces may thus be preferred, itwill be appreciated that some small fraction of synthetic fibers (e.g.,less than 10%, less than 5%, less than 3%, or less than 1%) may beincluded in some embodiments.

The exterior tissue layers may be of a through-air dried configuration.While conventional press-dried tissue was also tried in this exteriorlayer, this also resulted in less desirable hand-feel characteristics.Such conventional (not through-air-dried) tissue also undesirablypresses out any initially included texture, while through-air-driedprocessing preserves such pre-existing texture. While these alternativesmay not be preferred, they may still be suitable, for some uses. Variousother possible paper, tissue or nonwoven manufacturing techniques basedon dry crepe, through-air drying and combinations thereof withproduction equipment sold by Valmet Oyj, Voith GmbH & Co, Andritz AG,Toscotec S.p.A. and others that will be apparent to those of skill inthe art may also be suitable in at least some embodiments. Othersuitable tissue or nonwoven manufacturing techniques, include but arenot limited to: dry crepe technique (DCT), structured tissue or newtissue technology (NTT), Valmet QRT, Voith GmbH & Co. ATMOS or CascadesATAD, Andritz AG TEX, ETAD and others that will be apparent to those ofskill in the art may also be suitable in at least some embodiments.

While use of polyethylene or another thermoplastic polymer having thedescribed tan delta characteristics eliminates any need for a chemicaladhesive to adhere the top and bottom surface layer to the thermoplasticlayer, it will be appreciated that in other embodiments, e.g., evenusing polypropylene or another material having poor tan deltacharacteristics, it may be possible to achieve a multi-layer substratethat does not delaminate, e.g., by using a chemical adhesive to providethe needed bonding.

The degree of lamination and strength of the bond between adjacentlayers typically depends on the temperature, pressing or contact time,and applied pressure associated with the calendaring operation.Temperature may be a primary variable responsible for bond strengthachieved, although pressure and time may also have an effect, and mayalso affect the resulting texture that is “embossed” into the pulp fibersurface layer, and the resulting bond pattern. Where the pulp fiberlayers provided on both exterior faces are embossed with a texture, theresulting multi-layer substrate exhibits a more “cloth-like” feel thatis drapable and less stiff, as compared to where only one of the twofaces is embossed with a texture. In addition, it was observed that allelse being equal, heavier tissue (i.e., greater lb weight) produces astiffer substrate. FIGS. 7A-7F illustrate various possible embossingpatterns that can be applied by the calendar rollers. It will beapparent that the possibilities are nearly limitless.

Temperatures applied during calendaring may be at least 150° F., atleast 175° F., at least 200° F., from 200° F. to 400° F., or from 200°F. to 350° F. Applied pressure may be at least 50 psi, at least 100 psi,at least 150 psi, at least 200 psi, from 100 psi to 1000 psi, or from300 psi to 600 psi. Contact time (time at the given pressure and/ortemperature) may be at least 100 ms, at least 200 ms, from 100 ms to 5s, from 200 ms to 1 s, or from 200 ms to 500 ms.

Such a manufacturing process may be attractive, e.g., as compared totraditional non-woven substrate manufacture, as it may not require anyfiber processing, water usage, water filtration, drying steps, loss ofwood pulp during processing, and the like. In addition, the presentcalendaring process may allow for greater production line speeds (e.g.,up to 900 m/min, typically from 50 m/min to 600 m/min) as compared tospinlace manufacturing conventional blended substrates (that are notmulti-layer), which are at significantly lower line production speeds.

Increased line speed results in decreased contact time (all else beingequal). To provide the desired good bonding, higher line speed may beaccommodated by increasing web surface temperature (so shorter contacttime is needed), increasing the roller diameter (thus increasing contacttime), or increasing applied pressure (nip pressure). By way of example,for every 25 m/min increase in line speed, temperature can be increasedby about 5% (in ° C.) to maintain bonding level).

With respect to embossed textures, it was observed that “pin” textures(e.g., associated with fine dots) can result in tearing of the top andbottom surface layers, as the fibers get caught on the pins. Thus,textures that are formed using more of a “flat bar” type contact versusa sharp “pin” may be preferred, as such larger features do not result insuch tearing. In addition, it was observed that when manufacturing suchsubstrates through a calendaring operation, that the thermoplastic“cheese” layer should be narrower in width than the top and bottomsurface “bread” layers in order to further minimize complications duringmanufacture. From such a processed multi-layer laminated web, individualsized wipes may be cut to the desired size. Edges of the web that maynot include the thermoplastic “cheese” layer could be cut away duringsuch cutting, if desired.

The present substrates also provide for pulp reinforcement withpolymeric fibers, the ability to modulate the substrate stiffness bychanging the pattern applied during calendaring (e.g., see the variouspatterns of FIG. 1E), the ability to modulate stiffness and tensilestrength characteristics by texturing on one or both of the substratefaces, the ability to provide for relatively higher quat release even athigher pulp fractions, and more uniform lotion release, with bettermileage, as described in Applicant's application Ser. No. 16/042,690,filed Jul. 23, 2018, due to the high pulp content.

Without departing from the spirit and scope of this invention, one ofordinary skill can make various changes and modifications to theinvention to adapt it to various usages and conditions. As such, thesechanges and modifications are properly, equitably, and intended to be,within the full range of equivalence of the following claims.

The invention claimed is:
 1. A multi-layer substrate comprising: (a) atop surface layer consisting of: pulp fibers formed by one of thefollowing processes: airlaid, wetlaid, carded webs, thermal bonded,through-air bonded, thermoformed, hydroentangled, or chemically bondedand any combinations thereof; (b) a middle layer comprising athermoplastic material comprising polyethylene; (c) a bottom surfacelayer consisting of: pulp fibers formed by one of the followingprocesses: airlaid, wetlaid, carded webs, thermal bonded, through-airbonded, thermoformed, hydroentangled, or chemically bonded and anycombinations thereof; and (d) a cleaning composition loaded onto saidmulti-layer substrate wherein a fluid pathway through the thermoplasticmaterial allows the cleaning composition to travel from the top surfacelayer to the bottom surface layer; (e) wherein the multi-layer substrateis void of any chemical adhesives, the thermoplastic material instead,when melted, bonding to groups of fibers in the top surface layer andthe bottom surface layer that are in direct contact with thethermoplastic material as it melts and fractures, forming fluidpathways; and (f) wherein the middle layer is melted from thepolyethylene, wherein the polyethylene is initially in the form of aliquid impervious thin film, which becomes porous upon melting so as toprovide the fluid pathway through which the cleaning composition is ableto travel both from the top surface layer to the bottom surface layerand from the bottom surface layer to the top surface layer.
 2. Themulti-layer substrate of claim 1, wherein the cleaning compositioncomprises a quaternary ammonium compound.
 3. The multi-layer substrateof claim 2, wherein at least 50% of a quaternary ammonium compoundincluded in the cleaning composition loaded onto the multi-layersubstrate is released from the multi-layer substrate to a surface beingcleaned.
 4. The multi-layer substrate of claim 1, herein the cleaningcomposition comprises an organic acid.
 5. The multi-layer substrate ofclaim 1, wherein the top and bottom surface layers are wetlaid nonwovenmaterials selected from the following group: through-air-dried material,a press-dried tissue material, a DCT tissue material or a structuredtissue material.
 6. The multi-layer substrate of claim 1, wherein thethermoplastic material of the middle layer is a film having a thicknessfrom 0.01 mm to 0.05 mm.
 7. The multi-layer substrate of claim 1,wherein the multi-layer substrate includes: (i) unbound regions wherethe thermoplastic material is not bound to the adjacent fibers of thetop or bottom surface layer; and (ii) bound regions where thethermoplastic material is bound to the adjacent fibers of both the topand bottom surface layer.
 8. The multi-layer substrate of claim 7,wherein the unbound regions correspond to raised texture featuresembossed in the top or bottom surface layer.
 9. The multi-layersubstrate of claim 8, further comprising a gap associated with theunbound region in which the cleaning composition is stored.
 10. Themulti-layer substrate of claim 1, wherein no adhesive is present betweenthe thermoplastic material middle layer and the top and bottom surfacelayers, but rather the melted thermoplastic material directly bonds togroups of fibers in the top surface layer and the bottom surface layer,the melting and fracturing of the thermoplastic material forming anirregularly patterned bonded region between the thermoplastic materialmiddle layer and the adjacent top and bottom surface layers.
 11. Amulti-layer substrate comprising: (a) a top surface layer consisting of:pulp fibers formed by one of the following processes: airlaid, wetlaid,carded webs, thermal bonded, through-air bonded, thermoformed,hydroentangled, or chemically bonded and any combinations thereof; (b) amiddle layer comprising a thermoplastic material having a tan deltavalue of 0.2 to 0.4 within the temperature range of 100° F. to 350° F.;(c) a bottom surface layer consisting of: pulp fibers formed by one ofthe following processes: airlaid, wetlaid, carded webs, thermal bonded,through-air bonded, thermoformed, hydroentangled, or chemically bondedand any combinations thereof; and (d) a cleaning composition loaded ontosaid multi-layer substrate wherein a fluid pathway through the meltedthermoplastic material allows the cleaning composition to travel fromthe top surface layer to the bottom surface layer; (e) wherein themulti-layer substrate is void of any chemical adhesives, thethermoplastic material instead, when heated, bonding to groups of fibersin the top or bottom surface layer that are in direct contact with themiddle layer comprising the thermoplastic material as it melts; and (f)wherein the middle layer is melted from the thermoplastic material,wherein the thermoplastic material is initially in the form of a liquidimpervious thin film, which becomes porous upon melting so as to providethe fluid pathway through which the cleaning composition is able totravel both from the top surface layer to the bottom surface layer andfrom the bottom surface layer to the top surface layer.
 12. Themulti-layer substrate of claim 11, wherein the cleaning compositioncomprises a quaternary ammonium compound.
 13. The multi-layer substrateof claim 12, wherein at least 50% of a quaternary ammonium compoundincluded in the cleaning composition loaded onto the multi-layersubstrate is released from the multi-layer substrate to a surface beingcleaned.
 14. The multi-layer substrate of claim 11, wherein the cleaningcomposition comprises an organic acid.
 15. The multi-layer substrate ofclaim 11, wherein the top surface layer is a wetlaid material selectedfrom the following group: through-air-dried material, a press-driedtissue material, a DCT tissue material or a structured tissue material.16. The multi-layer substrate of claim 11, wherein the thermoplasticmaterial of the middle layer is a film having a thickness from 0.01 mmto 0.05 mm.
 17. The multi-layer substrate of claim 11, wherein thethermoplastic material of the middle layer comprises polyethylene. 18.The multi-layer substrate of claim 11, wherein the multi-layer substrateincludes: (i) unbound regions where the thermoplastic material is notbound to adjacent fibers of the top or bottom surface layer; and (ii)bound regions where the thermoplastic material is bound to adjacentfibers of both the top and bottom surface layer.
 19. The multi-layersubstrate of claim 18, wherein the unbound regions correspond to raisedtexture features embossed in the top or bottom surface layer.
 20. Themulti-layer substrate of claim 19, further comprising a gap associatedwith the unbound region in which the cleaning composition is stored.